Circuit breaker with arc chute short circuiting sections of the arc



G. E. JANSSON CIRCUIT BREAKER WITH ARC CHUTE SHORT May 19, 1953CIRCUITING SECTIONS OF THE ARC 2 Sheets-Sheet 1 Filed Jan. 24, 1950CIRCUIT BREAkER WITH ARC CHUTE SHORT CIRCUITING SECTIONS OF THE ARC May19, 1953 G E, JA SS'ON 2,639,353

Filed Jan. 24, 1950 2 Sheets-Sheet 2 H II $45M may finger t pe and apivoted blade like contact i2.

The fixed contact structure may comprise a plurality of current carryingcontacts and an arcing contact it provided with an arc runner as is wellknown, and is electrically connected to on line terminal of the breaker.

The movable contact I2 is suitably connected to an actuating mechanism(not shown) for actuating the movable contact between closed and opencircuit positions.

For the purpose or" extinguishing the are formed between the contactswhen a power circuit connected thereto is opened, an insulating arcextinguishing structure such as are chute it is arranged with respect tothe contacts so that the arc is drawn at the entrance of the chutedirectly opposite a gas blast supply conduit 95. The conduit forms partof any suitable known source of arc extinguishing fluid, which sourcemay also comprise a blast valve (not shown) joining the conduit to astorage tank and air compressor equipment (not shown).

The are chute M defines a narrow, diverging space into which the arc isdriven and. extinguished-by the blast and is formed by diverging endwalls l6 and l! and comparatively closely spaced parallel side walls l8and I9 more clearly shown in Figs. 2 and 3. The walls of the chute arecomposed of a suitable insulating material such as a molded laminatedstructure. The exhaust end of the chute is closed except for a laterallyextending conduit or stack 2! which directs the heated blast gases awayfrom the circuit breaker proper.

The are chute comprises a plurality of spaced diverging barriers orpartitions 22 of insulating material which form with the side walls l8and 19 a plurality of diverging arc passages 23. Partitions 22 arearranged across the arc chute it to extend transversely of the are.Within each interbarrier space or passage 23 is located a relativelyshort, oblong metallic tube M, as more clearly shown in Figs. 2 and 3,which is disposed between the ends of passage 23 which its longitudinalaxis transversely of the arc. Tubes 24 may be made of any suitable metalor alloy, but are preferably made of material of low electricalresistivity, such as bronze.

Tubes 24 may be mounted to closely fit against adjacent partitions,thereby permitting the free flow of the arc extinguishing blast throughthe passages 23. As shown the tubes 25 may be spaced from the partitions22 and side walls l8 and i9 along at least a part of their peripheryprovided that the spacing is sufficiently narrow to preclude the arefrom looping through the gap formed. End walls I6 and I! may be providedwith are runners 25 (one of which is shown in Fig. 1) which may beconductively connected to the adjacent tubes 24. Contact 13, which alsodefines an arc runner, may likewise be conductively connected to thenearest tube 24.

In order to concentrate the blast on the are section which is firstformed and is directed into the first passage 23, and to limit escape ofare products and compressed air through a slot 26 provided in arc chuteI4 for permitting movement of movable contact l2, the arc chute definesa nozzle structure 21 connected to supply conduit 15. The inner surfacesof nozzle 27 define a pair of finger shaped projections 28 (only one ofwhich is shown in Fig. 1) located one on each side of movable contact [2to cause a preponder ance of the blast to flow in the direction of thefirst formed are section and limit the amount of compressed air flowingthrough the blast passages 23 situated remotely from the first formedare section. Projections 28 form with the side walls of arc chute M apair of pockets or zones 29 (only one of which is shown in Fig. 1), oneon each side of contact 12, which tend to form an eddy in each zone,thus limiting the escape of are products and compressed air through slot26. Grooves 3i extending transversely of the direction of movement ofcontact I2 are provided in walls l8 and IQ of chute M for increasing thecreepage path across the area where the arc gap is formed uponseparation of the arcing contacts l I and I2.

The circuit breaker illustrated in Fig. 1 is shown with the cooperatingarcing contacts in the closed circuit position. An opening operation isinitiated by admission of gas under pressure to supply conduit l5 andthe actuation of blade contact l2 to the left to open the electriccircuit.

As the blade contact i2 is separated from the fixed arcing contact [3,an arc is drawn and a blast of gas of high intensity from the supplyconduit drives or loops the are into arc chute Hi and more particularlyinto passages 23.

In accordance with the invention the arc is driven into passages 23until the loops thereof contact the metallic tubes 24. When each tube 24is engaged by the end of the are loop driven into the particularpassage, the loop is short circuited by the tube, which is located nearthe upstream end of the adjacent partitions 22, thus dividing theparticular loop into two serially related arc sections interconnected bythe tube. The are loop is effectively short circuited, thus limiting itslength and energy.

Figs. 4 and 5 illustrate a modification of th invention so far describedas embodied in a modifled fluid blast circuit breaker. The circuitbreaker structure of Fig. 4 comprises relatively movable arcing contactssuch as finger type fixed contacts 32, pivoted blade like contact 33, asource of arc extinguishing fluid comprising a gas supply conduit 34,and an arc extinguishing structure.

The fixed contact 32 comprises a plurality of current carrying contactsand an arcing contact, as described heretofore, and is electricallyconnected'to one line terminal 35 of the breaker.

'The movable blade contact 33 is connected to the other line terminal(not shown), and is ac tuated by a connected rod (not shown) for movingcontact 33 between open and closed positions.

The are extinguishing structure comprising an arc chute 36 is mountedadjacent the arcing contacts 32 and 33 for extinguishing the are formedbetween the contacts when a power circuit connected thereto is opened.Arc chute '36 is formed by end walls 31 and 38 and comparatively closelyspaced parallel side walls 39 and 4|. The walls of the chute may becomposed of any suitable insulating material. The exhaust end of thearcchute is provided with an outlet 42 for directing the heatedblastgases away from the circuit breaker proper.

'Arcchute 36 further 'comprises'aplurality of parallel spaced barriersor partitions'43 of Veryiiig lengths mounted so as to extendtransversely 'of the arc and forming with the walls of the chute aplurality of spaced parallel passages 44.

The partition 43 immediately adjacent the right end of arc chute iifi'isillustrated as bein a little shorter than the partition immediatelyadjacent it. These two partitions, however, may be'equal in length. Theremainder of the partitions usually decrease in length progressivelyfrom right to left. Within each interbarrier space or passage 44 islocated a relatively short. hin'm'etallic tube 45, as illustrated inFig' 5, which is disposed between the ends of passage 44 and is usually'coaxially aligned therewith. Tubes "45 may be embedded in the adjacentpartitions, thereby permitting the free flow of the arc extinguishingblast through the passages 4 The tubes, however, may also be applied tothe walls of the partitions as shown in Fig. l or in any other suitablemanner.

'As illustrated in Fig.4 tubes 45 are spaced at varying distances fromthe upstream edges of passages 44, however, tubes t5 may be mounted atother distances without ceasing to. function as claimed.

As the blade contact 33 is separated from the fixed contact 32, an arcis formed which is rapidly elongated by a blast of gas of high intensityfrom supply conduit 34. The are loop is initially driven substantiallyperpendicularly to the direction of movement of Contact 33. Furtherelongation is limited to a plurality of loops extending within passages44 and occurs at a relatively slower rate than for the original are 100As described above, the arc loops into passages 44 and contacts themetallic tubes 45. When each tube is engaged'by the end of the arc loodriven into the particular passage, the'lcop is short circuited by thetube, thus dividing the loop into two parallel, serially related arcsections. Each arc loop is effectively short circuited, thus limitins,its length and energy.

Fig. 6 illustrates a magnetic blowout type of circuit breaker includingas elements thereof a pair of terminal studs 46 and 4'! for connectingthe circuit breaker to line conductors (not shown). The circuitinterrupter or breaker in Fig. 6 comprises essentially means for opening5 the circuit to form an arc, and an arc extinguish ing structure.Specifically, the circuit opening means ccmprisesfixed contacts 48 andE8, a fixed arcing contact 5!, and a movable arcing contact 52. Arcingcontact 52 is mounted on a lever 53 which'is pivotally mounted at t onextension 55 of the circuit breaker stud 45 and is operated by means ofa reciprocally movable rod 55. The operating rod 56 is suitablyconnected to an actu= atin'g mechanism (not shown) for operating themovable contact between closed and open circuit positions. Fig. 6illustrates the movable arcing contact 52 in a partially open position.The contacts 48, 49; 5| are electrically connected to the lower end "ofterminal stud 4'5. Accordingly, when the breaker is' connected in seriesin a power circuit and the arcing contacts are separated, an are formsacross the gap. indicated.

For the purpose of interrupting power arc, an arc extinguishingstructure, such as an arc chute 5'! may be mounted so as to receive thepower arc, which is under. the influence ofa magnetic blowout means 58.The. are. chute pref, erably is. disposed directly above the arcingcontacts; as shown, when the blow-out nieans act upward, but maybemounted in any other suitable location when the Pblowout means .act inother directions. The arcing contacts and the magnetic blowout structurecan assume any suitable known form so that a brief description thereofwill be sufficient. The magnetic blowout means 58 comprises a core 59,poles Bi, and a coil 62 which is inserted in the connection between theterminal stud 41, contact 5! and an arc runner 53, so that the arecurrent (as the arc travels along the runner) flows through the blowoutcoil in a manner well known in the art. Core 59 and poles El embrace atleast part of arc chute 57 for driving the are into the chute and towardthe exhaust end thereof.

Normally the current is carried in the closed circuit position of thebreaker by the spring biased contact 48. As the movable arcing contact52 is actuated to open circuit position, current is shunted from fixedcontact .58 sequentially to fixed contact 59 and to fixed arcing contact5!. As the arc is drawn by the movable arcing contact 52, the arcterminal on arcing contact 5! is transferred to are runner 53 which isusually an extension arm of the fixed arcing contact 51. As the movablearcing contact 52 reaches its full opening stroke the arc terminaltransfers from the movable arcing contact 52 to an arc runner M whichdirects the are into the are chute 51. As above set forth, the arcingcontact El and the arc runner 83 are electrically connected in serieswith the blowout coil 62 and stud M. Accordingly, the blowout coil isalready energized at the inception of the arc interruption to influencethe arc in a well known manner, i. e. to drive it into the arc chute 57in an expanding loop.

In accordance with the invention, are chute 5'! comprises a plurality ofspaced barriers or partitions 65 or suitable insulating material formingwith a pair of diverging side walls 66 a plurality of diverging arcpassages 57 parallel to each other. Partitions 555 are arranged acrossthe arc chute 51 to extend transversely of the arc. Within at least oneinterbarrier space or passage 6'! or within each passage ii? there islocated a relatively short, thin conductive ring or tube 658 which, forexample, may be a relatively short. thin rectangular metal tube, asshown in Figs. 6-8, mounted with its longitudinal axis extenclingtransversely of the are. It is desirable to use metallic tubes having aminimum thickness in order to retain the maximum possible passage acrosssectional arc: but nevertheless. these tubes must be thick enough to beable to carry heavy short circuit currents. Tube are mounted in anysuitable manner to fit against adjacent partitions and against the sidewalls, thereby perniitting the free how of air hot are products throughpassages 6?. The tubes are preferably disposed near the'tcp of the arc.chute in mag netic blowout breakers to insure that the arc will beretained within the chute on high short circuit currents and to permit apredetermined are elongation before short circuiti-ng portions of thearc. Arc energy increases as the arc length is increased to apredetermined critical length. i n ther elongation beyond this criticallength results in a decrease of are energy. In air blast breakers theshort-circuiting tubes are used to limit elongation at a low point ofthe ascending branch of the are energy curve and thereby also limit theare energy. vIn the air magnetic breaker, the short circuiting tubes areused merely. .to limit are elongation at a low point of the descendingbranch. of the arc. energy curve.

As the tubes are merely required to short cir cuit portions of the arc,they may be made of any suitable length providing sufiicient material tocarry the arc current, and may be in other equivalent forms, such aswire rings for example.

The length of the barrier portions extending from the tubes toward thecontacts is so chosen as to limit the arc elongation to the desiredvalue. As shown, the edges of the barriers meeting the arc may bestaggered to cause the arc to assume a zig-zag shape before being loopedinto the arc passages.

The barrier portions extending from the metallic tubes to the exhaustend of the arc chute are given a sufiicient length to cool the arcproducts to a safe temperature for discharge into atmosphere. Suchbarrier portions may be extensions of the barrier portions disposedtoward the contacts or may be differently arranged. Walls 66 divergetoward the exhaust end of the arc chute to cause expansion and resultingcooling of the air carrying arc products before its discharge intoatmosphere.

A resistor 69 may be conductively connected at one end thereof to anelectrode H which engages the are upon movement of the arc through arcchute 51. The other end of the resistor is connected to the end ofblowout coil 62 which is connected to contact thus forming an arc paththrough the current limiting resistor for aiding arc extinguishment.

As illustrated in Fig. 9, resistor 59 may be connected between a pair oftubes 8?: thereby providing a low resistance shunt across one of the arcportions. Under normal interrupting conditions the arc enters the arcchute 51 along the arc runners 63 and 64 and is driven by the magneticblowout means, the thermal effect of the arc and the chimney effect ofthe arc chute, into the passages 61. When each tube 68 is engaged by theend of the arc loop in the particular passage, the loop is shortcircuited by the tube, thus dividing the particular loop into twoparallel, serially related arc sections which are interconnected by tube68. Tube 68 may, for example, closely fit or hug the surfaces of thebarriers by which the interbarrier space or passage is bounded, therebyplacing the arc segments in close contact with the barriers for fur thercooling of the arc.

By limiting the length of the arc, by the use of the short circuitingtubes 68, the arc is confined within the chute during arc interruption.By providing tubes in all the arc chute passages the length of all thearc portions is limited. To obtain a cheaper construction and provide agreater cross section for the flow of gases, tubes may be inserted inonly one or less than all the arc chute passages, whereby the length ofonly part of the arc loops is limited.

Although but a few embodiments of the present invention have beenillustrated and described, it will be apparent to those skilled in theart that various changes and modifications may be made therein withoutdeparting from the spirit of the invention or from the scope of theappended claims.

It is claimed and desired to secure by Letters Patent:

1. An electric circuit interrupter comprising means for drawing an arcand an arc chute for receiving the are at one end thereof and exhaustingthe are products at the other end, said chute comprising a plurality ofspaced partitions of insulating material defining a plurality ofdiverging passages and arranged across said chute to extend transverselyof the arc and hollow tubes of conductive material mounted one withineach of said passages with the longitudinal axis of said tubes extendingtransversely of the arc for limiting arc elongation, each of said tubesbeing in contact with all the surfaces defining one of said passages.

2. An electric circuit interrupter comprising means for drawing an arc,an arc chute for receiving the are at one end thereof and exhausting theare products at the other end, and magnetic blowout means for drivingthe arc into said chute and toward the exhaust end thereof, said chutecomprising a plurality of spaced partitions of insulating materialdefining a plurality of passages and arranged across said chute toextend transversely of the arc, hollow tubes of conductive materialmounted near the exhaust ends of said passages with the longitudinalaxis of said tubes extending transversely of the are for limiting arcelongation, each of said tubes being in contact with all the surfacesdefining one of said passages, and a resistor connected between a pairof adjacent hollow tubes for limiting arc current.

3. An electric circuit interrupter comprising means for drawing an arc,an arc chute for receiving the arc at one end thereof and exhausting theare products at the other end, and means for driving the are into saidchute and toward, the exhaust end thereof, said chute comprising aplurality of spaced partitions of insulating material arranged acrosssaid chute and extending transversely of the arc to define a pluralityof arc passages and metallic tubes mounted between said partitions, eachof said tubes being in contact with all the surfaces defining one ofsaid passages and spaced therefrom along at least a part of itsperiphery for limiting arc elongation.

4. An electric circuit interrupter comprising means for drawing an arc,an arc chute for receiving the arc at one end thereof and exhausting theare products at the other end, a source of fluid under pressure fordriving the are into said chute and toward the exhaust end thereof, saidchute comprising a plurality of spaced partitions of insulating materialarranged across said chute to define a plurality of passages extendingtransversely of the arc, a pair of arc runners mounted at the upstreamend of said chute for directing the arc, and metallic tubes mountedbetween said partitions within said passages downstream of said arerunners for limiting arc elongation, each of said tubes being in contactwith all the surfaces defining one of said passages, at least one ofsaid are runners being conductively connected to at least one of saidtubes.

5. An electric circuit interrupter comprising means for drawing an are,an arc chute for receiving the are at one end thereof and exhausting thearc products at the other end, and magnetic blowout means embracing atleast a part of said chute for driving the are into said chute andtoward the exhaust end thereof, said chute comprising a plurality ofspaced partitions of insulating material defining a plurality ofpassages arranged across said chute to extend transversely of the arcand hollow tubes of conductive material mounted near the exhaust end ofsaid passages to limit are elongation, each of said tubes being incontact with all the surfaces defining one of said passages.

6. An electric circuit interrupter comprising means for drawing an arcand an arc chute for receiving the are at one end thereof and exhaustingthe are products at the other end, said chute comprising a pair of sideWalls, a plurality of spaced partitions of insulating material extendingfrom one of said walls to the other transversely of the arc to define aplurality of passages, and tubes of metal of low resistivity mountedwithin and surroundin said passages for limiting arc elongation.

7. An electric circuit interrupter comprising means for drawing an arcand an arc chute for receiving the are at one end thereof and exhaustingthe arc products at the other end, said chute comprising a pair ofrelatively closely spaced side walls, a air of relatively widely spacedend plates extending between said side walls, and a plurality of spacedpartitions of insulating material disposed between said end plates andextending from one of said side walls to the other transversely of thearc to define a plurality of passages, and metallic ring inserts of lowresistivity'mounted between adjacent partitions and surrounding saidpassages for limiting arc elongation.

8. An electric circuit interrupter comprising means for drawing an arcand an arc chute for receiving the are at one end thereof and exhaustingthe are products at the other end, said chute comprising a pair ofrelatively closely spaced side walls, a pair of relatively widely spacedend plates extending between said side walls and a plurality of spacedpartitions of insulating material disposed between said end plates andextending from one of said side walls to the other transversely of thearc to define a plurality of passages, and metallic hollow cylindricalinserts of low resistivity mounted one between each pair of adjacentpartitions and surrounding said passages near the upstream ends thereoffor limiting arc elongation.

9. An electric circuit interrupter comprising means for drawing an arcand an arc chute for receiving the are at one end thereof and exhaustingthe arc products at the other end, said chute comprising a "pair of sidewalls, a plurality of spaced partitions of insulating material extendingfrom one of said walls to the other transversely of the arc to define aplurality of passages, and metallic tubes of substantially less lengththan said partitions mounted within and surrounding said passages forlimiting arc elongation, said tubes being embedded in adjacentpartitions.

10. An electric circuit interrupter comprising means for drawing an arcand an arc chute for receivin the are at one end thereof and exhaustingthe are products at the other end, said chute comprising a pair ofrelatively closely spaced side walls, a pair of relatively widely spacedend plates extending between said side walls and a plurality of spacedpartitions of insulating material disposed between said end plates andextending from one of said side walls to the other transversely of thearc to define a plurality of passages, and metallic inserts formingtubes mounted within and closely fitting against adjacent partitions andsaid side walls for limiting arc elongation, said tubes being ofsubstantially less length than said partitions and disposed intermediatethe ends thereof.

GUSTAV E. JANSSON.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,243,039 Ludwig et a1 May 20, 1941 2,272,380 Ludwig et al.Feb. 10, 1942 2,285,643 Beiersdorf et al. June 9, 1942 2,451,669Eichenberger Oct. 19, 1948

